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Biomedical subjects

M Blumenstein

Publications and source records attributed to M Blumenstein.

At least 19 recordsLinked to original sources
PubMed1996

Plasma therapy at Klinikum Grosshadern: a 15-year retrospective.

Immediately after the availability of highly permeable membranes in 1979, membrane plasma separation was introduced as a mode of extracorporeal blood purification by the nephrology group at Klinikum Grosshadern of the Ludwig Maximilians University of Munich (F.R.G.). The new therapy was applied primarily in the management of immunologically mediated renal and extrarenal disorders as well as in paraproteinemias. We also have witnessed a widespread application of this extracorporeal treatment as a last resort in otherwise refractory clinical conditions. Over the years, the group at Grosshadern has contributed to the development, as well as to the laboratory and clinical testing, of new plasma separation membranes, simplified plasmapheresis formats (e.g., spontaneous membrane plasma separation), and several plasma fractionation procedures (e.g., cascade filtration, adsorption). Whenever indicated and possible, plasma fractionation procedures, rather than unselective plasma exchange, are performed in an appropriate clinical situation.

Chemical Fractionation↗
PubMed1993

The novel subset of CD14+/CD16+ blood monocytes is expanded in sepsis patients.

Staining with CD14 and CD16 monoclonal antibodies will identify two monocyte subpopulations in human blood: a major population of regular monocytes, which strongly expresses the CD14 antigen (CD14++), and a minor population with weak expression of CD14 and expression of the CD16 antigen (CD14+/CD16+ cells). As shown herein, the latter cells account for 45 +/- 22 cells/microL and 9% +/- 5% of the monocytes in healthy control donors (n = 35). In septicemia patients, the CD14+/CD16+ cells can become a major population, with more than 50% of all monocytes in 3 of 18 patients and with more than 500 cells in 4 of 18 cases. There was no correlation of CD14+/CD16+ cells to any clinical parameter except for CD14+/CD16+ percentage and body temperature (P = .013). The CD14++ regular monocytes showed a substantial decrease in CD14 antigen density in 9 of 11 patients. Three-color immunofluorescence shows that the CD14+/CD16+ monocytes in septicemia patients when compared with the CD14++ monocytes exhibit a higher level of class II antigen and a lower level of CD11b and CD33 antigens, consistent with a more mature nature of the CD14+/CD16+ cells. Levels of interleukin-6 (IL-6) were increased in septicemia patients; 3 of 5 patients with high numbers of CD14+/CD16+ cells (> 200/microL) had high levels of IL-6 (> 250/U/mL). These data suggest that septicemia may lead to substantial changes in blood monocyte composition and this may be related to elevated levels of cytokines such as IL-6.

Adult↗
PubMed1993

Lipid apheresis by hemoperfusion: in vitro efficacy and ex vivo biocompatibility of a new low-density lipoprotein adsorber compatible with human whole blood.

To date, selective extracorporeal low-density lipoprotein (LDL) removal can only be performed from plasma; that is, a plasma-cell separation step using a centrifuge or a plasma membrane separator is necessary initially. This article characterizes a new polyacrylate-based LDL adsorber directly applicable to whole blood. In vitro single-pass hemoperfusion tests using pooled donor blood showed quantitative adsorption of atherogenic LDL-cholesterol (LDL-C) and complete recovery of protective high-density lipoprotein C. Fibrinogen, another independent risk factor of atherosclerosis, was also adsorbed to a lesser extent. Single-pass ex vivo biocompatibility using fresh donor blood on-line was excellent and resulted in minimal cell loss. Neither signs of hemolysis nor activation of monocytes (interleukin-1 production) were detected. Only slight activation of leukocytes (elastase release) and thrombocytes (platelet factor 4 secretion) as well as of coagulation (thrombin-antithrombin complex formation) and complement (C3a, C5a generation) was observed. Under the experimental conditions used, the optimal anticoagulation regimen was 0.5 IU heparin plus 0.375 mg citrate/ml blood. Priming the column with a buffer of pH 7.4 containing heparin, citrate, and Ca2+ is recommended. In conclusion, this new adsorber exhibited selective LDL-C adsorption in vitro combined with excellent ex vivo biocompatibility and thus holds great promise for a successful clinical application in a closed-loop system in patients.

Acrylic Resins↗
PubMed1992

A beta-turn is present in the 392-411 segment of the human fibrinogen gamma-chain. Effects of structural changes in this segment on affinity to antibody 4A5.

The interaction between fibrinogen gamma-peptide 392-411, LTIGEGQQHHLGGAKQAGDV, and monoclonal antibody 4A5, an antibody with a high affinity for both for the peptide and native fibrinogen, is being studied as a model for peptide-antibody interaction. Two-dimensional NMR studies of the free peptide at pH 5.2 indicated the presence of a significant population, about 60%, of type II beta-turn, spanning residues Gln407-Asp410. At pH 2.7, little, if any, turn structure is present. The D-Ala409 analog, which, for steric reasons, would be expected to preserve the beta-turn, and the L-Ala409 analog, which would not be expected to have this conformational feature, were synthesized, and NMR studies confirmed the respective structural predictions. The affinity of the D-Ala analog for antibody 4A5 is even greater than that displayed by native gamma 392-411, while the affinity of the L-Ala analog is less than one-tenth that of the native peptide. Both conformational and steric effects involving residues 407-410 may be important in recognition by antibody 4A5. Since gamma 392-411 includes a platelet receptor binding locus of fibrinogen, and this and related peptides are inhibitors of platelet aggregation, the D-Ala409 and L-Ala409 analogs were tested for platelet binding. Neither of the analogs displays any measurable platelet binding, indicating that the recognition requirements for the platelet receptor differ considerably from those for antibody 4A5.

Amino Acid Sequence↗
PubMed1992

Differential expression of cytokines in human blood monocyte subpopulations.

Cytokine expression was analyzed in CD14++ regular monocytes and in the novel subset of CD14+/CD16+ small monocytes. Biologic activity for tumor necrosis factor (TNF), interleukin-1 (IL-1), and IL-6 in the supernatant of elutriator-enriched, cell sorter-purified small monocytes was about 10-fold lower compared with regular monocytes when stimulated with lipopolysaccharide (LPS) for 12 hours. In CD14++ regular monocytes levels were 1,157 U x 10(-3)/mL, 158 U/mL, and 1,337 U/mL for TNF, IL-1, and IL-6, respectively. By contrast, CD14+/CD16+ small monocytes exhibited 137 U x 10(-3)/mL, 14 U/mL, and 60 U/mL for TNF, IL-1, and IL-6, respectively. Additional treatment with interferon-gamma enhanced production of TNF in both subsets, but CD14+/CD16+ small monocytes still exhibited lower levels. Stimulation of the monocyte subsets by platelet-activating factor gave the same pattern of results. Hybridization with 32P-labeled oligonucleotides specific for the respective cytokine messenger RNAs (mRNAs) showed a 10-fold lower prevalence of transcripts for TNF, IL-1, and IL-6, as well. By contrast, the constitutive expression of Glyceraldehyde-3-phosphate-dehydrogenase mRNA was 1.7-fold higher in the CD14+/CD16+ small monocytes. These data indicate that the novel subset of small monocytes is selectively suppressed in the expression of the cytokines TNF, IL-1, and IL-6, suggesting that these cells may comprise a deactivated type of cell. The expression of class II transcripts in the small monocytes is, however, similar to the regular monocytes, and the cell surface expression of class II protein about threefold increased. Thus, the novel subset of small monocytes appears to be a functionally distinct type of cell.

Antigens, CD↗
PubMed1992

In vitro desensitization to lipopolysaccharide suppresses tumour necrosis factor, interleukin-1 and interleukin-6 gene expression in a similar fashion.

Like blood monocytes, the human monocytic cell line Mono Mac 6 can be stimulated by lipopolysaccharide (LPS) at 1 microgram/ml to produce high levels of cytokines. When Mono Mac 6 cells are stimulated for 4-6 hr at 1 x 10(6)/ml, supernatants contain tumour necrosis factor (TNF) at an average of 60 U/ml and interleukin-6 (IL-6) at an average of 1000 U/ml. IL-1 is not detected in the supernatant, but after three freeze-thaw cycles cell-associated IL-1 can be detected (100 U/ml) and with similar amounts of IL-alpha and -beta. Preculture of Mono Mac 6 cells with LPS at 10 ng/ml for 3 days results in cells refractory to subsequent stimulation by LPS at 1 microgram/ml. In the refractory desensitized cells, production of all three cytokines is down-regulated, with a more than 10-fold reduction in protein production. For all three cytokines, this desensitization appears to be regulated at the transcript level, with a strong reduction in specific mRNA as detected by Northern blot analysis. Furthermore, Mono Mac 6 cells can be stimulated by Staphylococcus aureus (LPS contamination less than 10 pg/ml) to produce cytokines. This type of stimulus is unable to overcome desensitization, in that the secretion of TNF in LPS-precultured Mono Mac 6 cells was 10- to 100-fold lower than in Mono Mac 6 cells without LPS preculture. These data show that desensitization in Mono Mac 6 cells affects all three cytokines tested and that it extends to other activating signals, such as staphylococci.

Antigens, Bacterial↗
PubMed1992

Adsorption profile of commercially available adsorbents: an in vitro evaluation.

Adsorbents from four commercially available devices, Protein A-Sepharose (Immunosorba Protein A-62,5; Excorim KB, Lund Sweden), Tryptophan-PVA (Immusorba TR-350; Asahi Medical Co., Tokyo, Japan), Phenylalanine-PVA (Immusorba PH-350; Asahi Medical Co., Tokyo, Japan), and Dextran sulfate (Liposorber LA-15; Kanegafuchi Chemical Co. Ltd, Osaka, Japan) were tested under optimal in vitro conditions to determine their adsorption capability for several plasma constituents which are usually the target of plasma therapy. The parameters of interest were: double stranded DNA-antibodies (anti-dsDNA), antiglomerular basement membrane antibodies (anti-GBM), anti-acetylcholin receptor antibodies (AChRAb), circulating immune complexes (CIC), rheumatoid factor (RF), IgA, IgG, IgM, IgE, C3c, C4, LDL-cholesterol, total cholesterol, erythropoietin (EPO) and beta 2-microglobulin (beta 2M). The IgG auto antibodies, CIC and RF can be removed by Protein A-Sepharose, Try-PVA and Phe-PVA. IgG is best adsorbed by Protein A-Sepharose, while IgE can be removed efficiently by Try-PVA. Dextran sulfate is without doubt the best adsorbent for LDL-cholesterol. All four adsorbents bind also complement components C3c and C4. No significant adsorption was found for EPO and beta 2M. The four devices exhibit a quite different adsorption profile which can be used as a guide for the optimal selection of an adsorption column in clinical apheresis.

Adsorption↗
PubMed1991

Small (CD14+/CD16+) monocytes and regular monocytes in human blood.

Compared to the obvious phenotypic and functional heterogeneity of tissue macrophages, little information is available on subsets of blood monocytes. We have employed two-color immunofluorescence and flow cytometry for the definition of regular and small monocytes, the latter characterized by the low-density expression of CD14 and the strong expression of the CD16 (Fcy-RIII) antigen. These cells comprise 15% of the blood monocytes and they appear to be similar in phenotype to the alveolar macrophage. The CD14+/CD16+ small monocytes can perform phagocytosis and they produce reactive oxygen, while their capacity for cytokine production is strongly reduced when compared to regular monocytes. At this point it is still unclear as to whether the CD14+/CD16+ small monocytes comprise a specific level of activation or differentiation or a distinct sublineage of human blood monocytes.

Antigens, CD↗
PubMed1991

Monocyte phenotype and interleukin-1 production in patients undergoing haemodialysis.

The expression of MHC class II (HLA-DR) and complement receptor (CR1) surface molecules on CD 14+ monocytes were compared with the production of the monokine interleukin-1 beta (IL-1 beta) in patients with endstage renal disease undergoing maintenance haemodialysis (HD) with hollow fibre dialyzers containing cellulose (CE, n = 8) and polysulfone (PS, n = 7) membranes. Monocyte staining was performed in blood samples obtained at the beginning and after 3 h of HD. Analysis of surface marker expression was done by immunofluorescence staining and flow cytometry analysis. Specific fluorescence intensity for both CR1 and class II (HLA-DR) antigens was increased in patients treated with CE membranes at the beginning of a dialysis treatment when compared to healthy control values. Interestingly, after 3 h on dialysis a further increase was noted for CR1 complement receptor expression whereas the increased HLA-DR expression was no longer detectable. In contrast, specific fluorescence intensity for both antigens was not significantly different from controls, either before or after dialysis, in patients treated with PS. The capacity of peripheral blood mononuclear cells to produce IL-1 beta spontaneously in vitro in the two patient groups was found to parallel results on phenotypic expression of surface molecules. The present study demonstrates that functional signs of monocyte activation, as evidenced by an augmented IL-1 beta production, in some patients on long-term HD correlate with an increased expression of two functionally important monocyte surface marker molecules.

Adult↗
PubMed1990

Modulation of cytotoxicity of cytostatic drugs by hemodialysis in vitro and in vivo.

For most cytotoxic substances there are no established guidelines on how to deal with overdosage. Little is known about the dialysability of cytostatic drugs. To obtain further information, human plasma was incubated with cytostatic drugs and dialysed in vitro, using 'minimodules' with capillaries identical to those in clinical use. Cytotoxicity before and after dialysis was measured in a biological test system using permanent human lymphoblast cultures (LS2). The 20 cytostatic drugs studied were categorized as follows: (1) Dialysability in vitro. Good: methotrexate (MTX), 5-fluorouracil (5-FU/5-FUdR), cytarabine (ARAC), actinomycin D (DACT), mitomycin C (MMC), 4-OH-cyclophosphamide (4-OH-CPM), ifosfamide (IFO), melphalan (L-PAM), dacarbazine (DTIC), cisplatin (DDP). Intermediate: Adriamycin (ADM), 4'-epi-doxorubicin (4'-EA), carmustine (BCNU). Ineffective: daunorubicin (DNR), vincristine (VCR), vinblastine (VBL), vindesine (VDS), etoposide (VP-16), teniposide (VM-26), mitoxantrone (MITOX). These in vitro results cannot be transferred automatically into the in vivo situation because of specific drug distribution and metabolic rates. Considering pharmacokinetic data from the literature, the following recommendations can be made for practical clinical purposes. (2) Detoxification by hemodialysis in vivo. Possibly effective: MTX, 5-FU, MMC, CPM, IFO, L-PAM, BCNU, DTIC. Ineffective: ADM, 4'-EA, DNR, MITOX, DACT, VP-16, VM-26, VCR, VBL, VDS, ARAC, DDP.

Antineoplastic Agents↗
PubMed1990

Evaluation of phagocytic cell function in an ex vivo model of hemodialysis.

An ex vivo model of hemodialysis was used to evaluate the effect of dialysis membranes on phagocytic cell function. Blood was withdrawn continuously from healthy, non-uremic donors, heparinized, and pumped, single pass, through membrane modules under conditions which simulated normal dialysis conditions. The membrane modules contained membranes of cellulose, DEAE-substituted cellulose, or polysulfone. Blood was obtained from the module outlets for determination of complement activation, phagocyte elastase release, zymosan-induced phagocyte chemiluminescence, and monocyte interleukin-1 production. Significantly less complement activation occurred with the polysulfone and DEAE-substituted cellulose membranes than with cellulose membranes. Normal monocyte interleukin-1 production was not stimulated by any of the membranes used. In contrast, the cellulosic, but not the polysulfone, membranes primed the oxidative burst of the phagocytes and caused them to release elastase. DEAE-substituted cellulose had a lesser effect on elastase release than did cellulose and elastase release correlated significantly with the degree of complement activation. However, the correlation between complement activation and priming of phagocyte oxidative burst was weak, suggesting that membranes affect phagocyte oxidative metabolism through more than one mechanism. We conclude that some dialysis membranes stimulate the bacteriacidal functions of normal phagocytic cells, in part through complement-dependent mechanisms.

Humans↗
PubMed1990

Differential activation of monocytes in haemodialysis patients exposed to different types of membranes.

Peripheral blood mononuclear cells (PBMC) from haemodialysis patients treated with different types of membranes were isolated, incubated in vitro, and extracellular and cell-associated interleukin I (IL-1) assayed by radioimmunological methods. Extracellular IL-1 was low and not different from controls, regardless of the dialyser used. In contrast, cell-associated IL-1 was increased in patients treated with dialysers containing low-flux Cuprophan (CU, n = 5) and polyacrylonitrile sheet membrane (AN69, n = 5). Patients treated with dialysers containing high-flux polysulphone (PS, n = 7), and polymethylmethacrylate (PMMA, n = 8), exhibited no increase in cell-associated IL-1 under these conditions. To elucidate the mechanism of the activation, aqueous extracts of dialysers containing CU, PS, and AN69 were tested for their ability to induce IL-1 generation in PBMC from healthy donors. Extracts from unrinsed CU-containing dialysers caused significant IL-1 synthesis and release, whereas incubation with extracts from dialysers containing PS and AN69 sheet membranes did not. Hence, although both CU and AN69 sheet-type dialysers result in activation of blood monocytes the mechanism of action appears to be different. We speculate that functional signs of PBMC activation as evidenced by increased spontaneous IL-1 production observed in some patients on long-term haemodialysis may result from extractable dialyser membrane material while in other instances direct cell membrane interactions or endotoxin transfer from the dialysate may be relevant.

Adult↗
PubMed1990

[Dialysability of cytostatic drugs. Experimental studies in vitro].

There are no established guidelines for detoxification for most cases of overdosage or intoxication with cytostatic drugs. Little is known about the dialysability of cytostatic drugs. To obtain further information on the dialysability of cytostatic drugs, human plasma was incubated with cytostatic drugs and dialysed in vitro using "mini-modules" with capillaries identical to clinical use. Cytotoxicity before and after dialysis was measured in a biological test system using permanent human lymphoblast cultures (LS2). The 20 cytostatic drugs studied could be categorised as follows: Good dialysability in vitro: methotrexate, 5-fluorouracil, cytarabine, actinomycin D, mitomycin C, 4-OH-cyclophosphamide, ifosfamide, melphalan, dacarbazine, cisplatin. Intermediate dialysability in vitro: adriamycin, epirubicin, carmustine. Ineffective dialysability in vitro: daunorubicin, vincristine, vinblastine, vindesine, etoposide, teniposide, mitoxantrone. These in vitro results cannot be transferred automatically into the in vivo situation because of specific drug distribution and metabolic rates. Considering pharmacokinetic data, the following recommendations can be made for practical clinical purposes: Detoxification by hemodialysis in vivo: Possibly effective: Methotrexate, 5-fluorouracil, mytomicin C, cyclophosphamide, ifosfamide, melphalan, carmustine, dacarbazine. Ineffective: Adriamycin, epirubicin, daunorubicin, mitoxantrone, actinomycin D, etoposide, teniposide, vincristine, vinblastine, vindesine, cytarabine, cisplatin.

Antineoplastic Agents↗
PubMed1989

B cell lymphokines in human systemic lupus erythematosus.

B lymphocytes of patients with systemic lupus erythematosus were studied to determine if they were intrinsically hyperresponsive to lymphokine mediators. Peripheral blood B cells from 25 lupus patients and 16 normal individuals matched for age and sex were cultured with recombinant lymphokines. B cells both from patients and normal subjects did not show increased [3H]thymidine uptake when cultured with interleukins 1, 2, and 4. The addition of Staphylococcus aureus Cowan I as costimulant increased [3H]thymidine uptake by B cells of patients and normal subjects. In the absence of T cells these recombinant lymphokines did not increase in vitro IgG or IgM production by lupus or normal B cells. Other recombinant lymphokines, interleukin 3, interferon gamma, lymphotoxin, tumour necrosis factor, and colony stimulating factors for granulocytes and macrophages were tested on lymphocytes from smaller numbers of patients and controls. Most patients in this study had inactive disease and all data suggested that B cells from patients with inactive lupus were not hyperresponsive to the lymphokines tested. In addition, the use of lymphokine gene probes for interleukins 2, 3, and 4 did not show spontaneous expression of these genes in circulating lymphocytes.

Adult↗